The Guardian and Observer's 2012 Christmas charity appeal could receive a boost of up to £25,000 after one of the UK's biggest donation management agencies, Charities Trust, pledged to match readers' donations over the next 12 days.

The appeal is supporting eight charities that help people with a disability to fulfil their potential, in education, arts, sport and the workplace.

Over 12 days of giving, starting on Wednesday 12 December, the appeal will receive an additional top-up donation, up to the value of £2,000 per day from Charities Trust to mark its 25th birthday.

There is a further £1,000 set aside for a prize draw – one donor will win the chance to share the amount between the Guardian/Observer appeal and the charity of their choice.

The Guardian and Observer will be putting put their own social media weight behind the initiative over the next 12 days and will be urging followers and friends to support this year's appeal, using the Twitter hashtag #Gdn12DaysofGiving.

Charities Trust has handled major appeal funds, payroll giving and individual donations for a quarter of a century, launching products such as the My Giving Account and Sponsor Me to encourage donations.

Chief executive Linda Minnis said: "Every day we connect corporate and individual givers with the right beneficiaries in the most cost effective way. For the last 25 years, 100% of our focus has been dedicated to maximising charitable giving.

"It's nice to be able to give great appeals, like this one, the support it deserves. It's an investment that marks our milestone anniversary and our continued investment in growing the giving market."